慢性复合应激对大鼠学习和记忆及海马神经元神经颗粒素表达的影响

目的探讨慢性复合应激对大鼠学习和记忆功能及海马内神经元神经颗粒素(neurogranin,Ng)表达的影响。方法成年雄性Wistar大鼠随机分为对照组和复合应激组,复合应激组动物每天无规律交替暴露于复合应激原环境中,为期6周。应激结束后,用Morris水迷宫测试大鼠空间学习和记忆成绩,同时用免疫组织化学方法观察海马各亚区Ng表达的变化,并用RT-PCR技术分析各组大鼠海马Ng mRNA水平的变化。结果Morris水迷宫测试显示,应激组动物寻找隐蔽平台潜伏期明显短于对照组(P<0.05);应激组大鼠海马DG和CA3区Ng的蛋白表达水平明显高于对照组(P<0.05),而两组海马CA1区的Ng的免疫反应性无明显差别;与对照组相比,应激组动物的Ng mRNA水平亦明显上调(P<0.05)。结论慢性复合性应激大鼠的学习与记忆能力增强;Ng在海马中的表达和Ng mRNA转录水平增高,提示Ng参与了该增强机制。

EFFECT OF CHRONIC MUTIPLE STRESS ON SPATIAL LEARNING AND MEMORY AND ON NEUROGRANIN EXPRESSION IN RAT HIPPOCAMPAL NEURONS

Objective To examine the effect of chronic multiple stress on the spatial learning and memory function and the expression of neurogranin(Ng) in the hippocampus of adult rats.Methods Adult male Wistar rats were randomly divided into the control and stressed groups.Rats in the stressed group were irregularly and alternatively exposed to chronic multiple stress for 6 weeks.After the chronic multiple stress,all rats were tested for the performance of spatial learning and memory in Morris water maze.The expression of Ng protein and the level of Ng mRNA in the hippocampus were measured by immunohistochemical method and RT-PCR technique,respectively.Results After chronic multiple stress,the latency to find the hidden platform in Morris water maze was significantly shortened in the stressed group than that of the control group(P<0.05).Compared with that of the control group,the expression of Ng in the hippocampal area DG and CA3 was markedly increased in the stressed group(P<0.05),but no difference was observed in CA1 area.The level of Ng mRNA was also distinctively up-regulated in the hippocampus of the stressed group(P<0.05).Conclusion Thechronic multiple stress may enhance the spatial learning and memory function of the rat.Both the expression of Ng protein and the level of Ng mRNA are increased in the hippocampus.These results suggest that Ng may participate in the mechanism of enhanced learning and memory.